Hard disk drives are used in almost all computer system operations. In fact, most computing systems are not operational without some type of hard disk drive to store the most basic computing information such as the boot operation, the operating system, the applications, and the like. In general, the hard disk drive is a device which may or may not be removable, but without which the computing system will generally not operate.
The basic hard disk drive model was established approximately 50 years ago and resembles a phonograph. That is, the hard drive model includes a storage disk or hard disk that spins at a standard rotational speed. An actuator arm with a suspended slider is utilized to reach out over the disk. The arm carries a head assembly that has a magnetic read/write transducer or head for reading/writing information to or from a location on the disk. The complete head assembly, e.g., the suspension and head, is called a head gimbal assembly (HGA).
In operation, the hard disk is rotated at a set speed via a spindle motor assembly having a central drive hub. Additionally, there are tracks evenly spaced at known intervals across the disk. When a request for a read of a specific portion or track is received, the hard disk aligns the head, via the arm, over the specific track location and the head reads the information from the disk. In the same manner, when a request for a write of a specific portion or track is received, the hard disk aligns the head, via the arm, over the specific track location and the head writes the information to the disk.
Over the years, the disk and the head have undergone great reductions in their size. Much of the refinement has been driven by consumer demand for smaller and more portable hard drives such as those used in personal digital assistants (PDAs), MP3 players, and the like. For example, the original hard disk drive had a disk diameter of 24 inches. Modern hard disk drives are much smaller and include disk diameters of less than 2.5 inches (micro drives are significantly smaller than that). Advances in magnetic recording are also primary reasons for the reduction in size.
However, the decreased track spacing and the overall reduction in HDD component size and weight have resulted in problems with respect to the HGA. Specifically, as the component sizes shrink, a need for tighter aerial density arises. In other words, the HGA is brought physically closer to the magnetic media. In some cases, the HGA will reach “ground zero” or a slider/disk contact. The contact will result in a lot of well-known problems, such as disk wear, bouncing vibration, slider damage, and the like.
In addition, there is another problem with slider/disk contact when the slider leading edge is lower than the trailing edge, or when the slider has a negative pitch. That is, when the leading edge of the slider contacts the disk at the lower operational speeds associated with smaller drives, the friction between the disk and the leading edge will result in the leading edge remaining in contact with the disk surface. As such, the trailing edge of the slider will remain hung in the air (e.g., the slider will be at a negative pitch angle), such that the head (located at or around the trailing edge) will not be able to read to or write from the disk. This problem is particularly egregious when the drive is a load/unload drive and the slider is initially making negative pitch contact with a disk rotating at operational speed.
One solution to the problem of friction between the sliders leading edge and the disk is to provide lubrication between the slider and the disk surface to reduce the friction component. However, the introduction of a lubrication into the HDD results in additional problems such as splatter of lubricant on other components, running out of lubricant over long term operation, and the like. Therefore, what is needed is a reliable and repetitive method for reducing the friction forces between the leading edge of the slider and the disk surface during contact.